1. Field of the Invention
The present invention relates in general to data storage systems such as disk drives. This invention relates in particular to a read/write head for use in optical and magneto-optical data storage systems to enable hybrid transduction of data from, and to a storage medium. More specifically, the head allows the magnetic reading of data from the magnetic medium, and the magneto-optical or thermally assisted writing of data on the storage medium.
2. Description of Related Art
A conventional magnetic storage system includes a magnetic head that has a slider element and a magnetic read/write element, and is coupled to a rotary actuator magnet and a voice coil assembly by a suspension and an actuator arm positioned over a surface of a spinning magnetic disk. In operation, a lift force is generated by the aerodynamic interaction between the magnetic head and the spinning magnetic disk. The lift force is opposed by equal and opposite spring forces applied by the suspension such that a predetermined flying height is maintained over a full radial stroke of the rotary actuator assembly above the surface of the spinning magnetic disk.
Flying head designs have been proposed for use with optical and magneto-optical (MO) storage technology. One motivation for using the magneto-optical technology stems from the availability of higher areal density with magneto-optical storage disks than magnetic storage disks. However, despite the historically higher areal storage density available for magneto-optical disks drives, the prior art magneto-optical disk drive volumetric storage capacity has generally not kept pace with the volumetric storage capacity of magnetic disk drives.
One limiting factor in conventional optical reading heads is the low signal to noise ratio exhibited by such heads at high data transfer rates, since the frequency dependence of laser notse is typically exponential.
Another limiting factor is that optical reading heads require extensive alignment of the optical components and their respective polarizations, rendering the design, manufacturing and assembly of optical heads significantly complex.
Another factor that limits writing (or recording) on a magnetic disk at high data transfer rates (or frequencies) using conventional magnetic heads is the required high magnetic field and field gradient. High magnetic fields are difficult to achieve, particularly with narrow tracks and miniaturized heads, because it is difficult to channel magnetic flux through such narrow structures, and further because the small pole structure is hard to define due to its large aspect ratio (height/width), usually greater than 2:1.
Therefore, there is still a long felt and still unsatisfied need for a read/write head that is structurally significantly less complicated than optical reading devices, that requires minimal or no optical alignment, that can write at higher track densities, and that has better control of the data and servo tracks than conventional magnetic heads. It would also be desirable for the head to be capable of using an available heat source and a relatively weak magnetic field, such as 300 Oersteds, to write data on a data storage medium.